It has become a customary contemporary practice to compress data to reduce usage of resources, for example, during data storage and data communication. During data communication, a sequence of data blocks or data packets is communicated from one device to another device. Data blocks or data packets communicated later in the sequence are often changed in comparison to data blocks or data packets that have been communicated earlier. However, changes in individual elements inside these changed data blocks or data packets are considerably smaller than the original content of the data blocks or data packets. In other words, most of the elements inside the changed blocks are unchanged in comparison to the earlier data blocks or data packets. When such a sequence of data blocks or data packets is compressed using conventional encoders, often only a small compression ratio is achieved.
One conventional encoder-decoder (hereinafter referred to as “coded”) has been described in US patent document 20120219065 A1, titled “Processing of Image”. The conventional codec processes entire data blocks of an image or data sequence, and compares the entire data blocks with previous data blocks. The conventional codec encodes an unchanged data block to a predefined colour value or data value, and also encodes a changed data block as it is. This means that all the original data values in a changed data block are coded, and so a compression efficiency performance provided by the conventional encoder-decoder is not as great as potentially achievable.
In a patent document US2013/0315307A1 (Karkkainen et al.), there is described an encoder that employs changed/unchanged bits to express whether a corresponding data block, for example inside an image frame, has changed or not. Although such an approach functions well, it is feasible to enhance its performance significantly.
Moreover, another conventional codec (http://en.wikipedia.org/wiki/Delta encoding) employs delta coding for processing data. In delta coding, a difference (namely, a delta value) between a current data element and a previous data element is written or transmitted. However, such delta values often generate new data values that are potentially not present in the data or otherwise enlarges the dynamic of the data values, and therefore, an increase entropy of the data thereby potentially arises.
Therefore, there exists a need for such a codec for compressing data that is more efficient in comparison to the conventional codecs.